Search

International audience; This study presents a miniaturized 3-methyl-2-benzothiazolinone hydrazone hydrochloride-assay (MBTHassay) 1 , optimized for high-throughput measurement of shrimp phenol oxidase activities and the screening of potential inhibitors of post-mortem melanosis. To validate this approach, assay parameters, including limit of detection and dynamic range, were compared to values obtained for DOPAchrome-assay, used here as a reference method. A reliable high-throughput automatized analysis was also performed, under standardized parameters, in order to compare and characterize 40 potential inhibitors of phenol oxidase activities. Among the selected molecules, twenty showed inhibitory action. Enzyme-inhibitor dissociation constant (K i), median inhibitor concentration (IC 50) and inhibition modes could be determined for nine of them. 4-Hexylresorcinol, Nphenylthiourea L-cystein and glutathione displayed K i values lower than sulfite salts (Na 2 S 2 O 5 and Na 2 SO 3) used as positive controls.

International audience; Front-face fluorescence spectroscopy was used as a rapid tool for assessing freshness of whiting fish (Merlangius merlangus) fillets stored at 4 ± 1 °C for up to 12 days under different conditions. Some physicochemical analysis [i.e., water content, pH, peroxide value, thiobarbituric acid reactive substances (TBARS)] were performed. With increasing storage time, the TBARS and pH values increased progressively in all whiting fish fillets, in particular for those exposed to light. Principal component analysis and factorial discriminant analysis applied separately to the tryptophan (excitation: 290 nm, emission: 305–450 nm) and nicotinamide adenine dinucleotide (NADH) (excitation: 340 nm, emission: 360–600 nm) spectra gave only a slight discrimination between the investigated whiting fish fillets. These results were improved when data from all the fluorescence spectra were analyzed jointly, since nearly three-quarters of samples were correctly classified. The best results were obtained by concatenating the fluorescence and physicochemical data sets, giving more than 90% of correct classification.